Bag Filling And Packaging Method And Bag Filling And Packaging Apparatus

ABSTRACT

A bag mouth correcting device is disposed between a deaeration station and a sealing station. The correcting device has a pair of bar-shaped guide members. The guide members extend in the direction of movement of a bag, and an expected sealing area of the bag passes between the guide members. The guide members are disposed at a height position corresponding to the expected sealing area. The guide members extend gradually upward and the space therebetween gradually decreases as the distance from the upstream side increases toward the downstream side in the direction of movement of the bag. While passing between the guide members, the tilted bag mouth is corrected to a substantially uncurled state.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a bag filling and packaging method and apparatus. More particularly, the present invention relates to a bag filling and packaging method and apparatus in which a plurality of pairs of laterally spaced grippers are provided at equal spaces to hold bags in a vertically suspended position, with their bag mouths facing upward, by gripping the laterally opposite side edges of each bag with a pair of grippers, and the bags held in this way are each moved intermittently or continuously along a predetermined planar path to sequentially undergo predetermined packaging processes such as opening of the bag mouth, filling of an article to be packaged into the bag, steam-replacement deaeration, and sealing of the bag mouth.

2. Background Art

In bag filling and packaging of food products or the like, steam-replacement deaeration may be performed in which the air in a bag filled with an article to be packaged is replaced with steam for deaeration. An apparatus in which such steam-replacement deaeration is carried out is disclosed, for example, in Japanese Patent Application Laid-Open Publication No. Hei 9-95311. To carry out steam-replacement deaeration, a bag filled with an article to be packaged is moved to a station for a steam-replacement deaeration step, where a steam jet nozzle is inserted into the bag, and the pair of grippers gripping the laterally opposite side edges of the bag are moved away from each other by a predetermined distance to bring the bag mouth into a tensed state. In this state, steam is injected into the bag from an outlet port at the distal end of the nozzle. Thereafter, with the bag mouth kept in the tensed state, the nozzle is removed from the bag, and the injection of steam is stopped. Then, with the bag mouth kept in the tensed state, the bag is moved to a station where a sealing step is carried out. The steam jet nozzle used in the steam-replacement deaeration usually has an insert part to be inserted into the bag, which is formed into a flat cross-sectional configuration in order to narrow the opening of the bag mouth at portions thereof near the lateral edges of the nozzle at which the side wall sheets of the bag are separate and open when the bag mouth is tensed. In addition, the bag is moved to the sealing station, with the bag mouth kept in the tensed state, and sealed in this state, thereby preventing air from entering the bag from the outside.

However, steam blown into the bag may exert an adverse effect on sealing of the bag mouth carried out in the subsequent step. That is, because the specific gravity of steam is less than that of air, steam injected into the bag tends to rise in the bag and to flow out of the bag. Steam rising in such a manner may warm and expand a part of the bag mouth including an expected sealing area thereof. This may cause the side wall sheets of the bag to tilt away from each other at the edge of the bag mouth, resulting in the bag mouth edge being curled (curved). If the expected sealing area of the bag mouth is sealed in this state, the expected sealing area may be undesirably folded or creased, which may result in degradation of the appearance of the bag, and may cause a sealing failure.

A conventional way of coping with the above-described problem is to seal the bag below the curled portion. With the conventional method, however, the bag mouth edge is not sealed; therefore, the bag becomes unattractive in appearance as a finished product. In addition, dust may undesirably enter the bag mouth from the bag mouth edge where the side wall sheets are not in close contact with each other. Further, because the seal width is reduced, problems may occur in terms of seal strength.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-described problems associated with the background art.

Accordingly, an object of the present invention is to provide a bag filling and packaging method and apparatus capable of properly sealing the expected sealing area even if the bag mouth edge is curled in the deaeration step, or capable of minimizing the degree of curl, thereby allowing sealing to be performed without hindrance.

The present invention provides a bag filling and packaging method in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging method includes a steam-replacement deaeration step of moving a bag filled with an article to be packaged to a deaeration station having a steam jet nozzle (hereinafter referred to simply as “nozzle”), inserting the nozzle into the bag, moving the grippers away from each other by a predetermined distance to bring a bag mouth of the bag into a tensed state, injecting steam from the nozzle to replace air in the bag with the steam, and removing the nozzle from the bag, with the bag mouth kept in the tensed state. The bag filling and packaging method further includes a sealing step of moving the bag to a sealing station, with the grippers kept away from each other by the predetermined distance, and sealing an expected sealing area set at the bag mouth of the bag. Further, the bag filling and packaging method includes a bag mouth correcting step of passing the expected sealing area of the bag between a pair of guide members disposed facing each other across the bag in the direction of thickness of the bag in the course of moving the bag from the deaeration station to the sealing station, thereby allowing the side wall sheets of the bag to be brought close to each other at the expected sealing area.

In addition, the present invention provides a bag filling and packaging method in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging method includes a steam-replacement deaeration step of moving a bag filled with an article to be packaged to a deaeration station having a nozzle, inserting the nozzle into the bag, moving the grippers away from each other by a predetermined distance to bring a bag mouth of the bag into a tensed state, injecting steam from the nozzle to replace air in the bag with the steam, and removing the nozzle from the bag, with the bag mouth kept in the tensed state. The bag filling and packaging method further includes a sealing step of moving the bag to a sealing station, with the grippers kept away from each other by the predetermined distance, and sealing an expected sealing area set at the bag mouth of the bag. In the steam-replacement deaeration step, after the nozzle has been inserted into the bag, the nozzle is pressed between a pair of pressing members through the expected sealing area of the bag, and the pressing members are separated from the nozzle before the nozzle is removed from the bag.

In addition, the present invention provides a bag filling and packaging method in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging method includes a steam-replacement deaeration step of moving a bag filled with an article to be packaged to a deaeration station having a nozzle, inserting the nozzle into the bag, moving the grippers away from each other by a predetermined distance to bring a bag mouth of the bag into a tensed state, injecting steam from the nozzle to replace air in the bag with the steam, and removing the nozzle from the bag, with the bag mouth kept in the tensed state. The bag filling and packaging method further includes a sealing step of moving the bag to a sealing station, with the grippers kept away from each other by the predetermined distance, and sealing an expected sealing area set at the bag mouth of the bag. In the steam-replacement deaeration step, after the nozzle has been inserted into the bag and the bag mouth has been brought into a tensed state, the expected sealing area of the bag is partially sealed at the opposite sides of the nozzle in the width direction of the bag.

In addition, the present invention provides a bag filling and packaging method in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging method includes a steam-replacement deaeration step of moving a bag filled with an article to be packaged to a deaeration station having a nozzle, inserting the nozzle into the bag, moving the grippers away from each other by a predetermined distance to bring a bag mouth of the bag into a tensed state, injecting steam from the nozzle to replace air in the bag with the steam, and removing the nozzle from the bag, with the bag mouth kept in the tensed state. The bag filling and packaging method further includes a sealing step of moving the bag to a sealing station, with the grippers kept away from each other by the predetermined distance, and sealing an expected sealing area set at the bag mouth of the bag. Further, the bag filling and packaging method includes a cooling step of blowing a cooling gas toward the bag to cool the expected sealing area in the course of moving the bag from the deaeration station to the sealing station.

In addition, the present invention provides a bag filling and packaging method in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging method includes a steam-replacement deaeration step of moving a bag filled with an article to be packaged to a deaeration station having a nozzle, inserting the nozzle into the bag, moving the grippers away from each other by a predetermined distance to bring a bag mouth of the bag into a tensed state, injecting steam from the nozzle to replace air in the bag with the steam, and removing the nozzle from the bag, with the bag mouth kept in the tensed state. The bag filling and packaging method further includes a sealing step of moving the bag to a sealing station, with the grippers kept away from each other by the predetermined distance, and sealing an expected sealing area set at the bag mouth of the bag. In the sealing step, a pair of hot plates disposed at the opposite sides, respectively, of the bag are moved from respective standby positions each apart from the bag by a predetermined standby distance to respective restricting positions where the hot plates are each apart from the bag by a predetermined restricted distance shorter than the standby distance and where the upper edges of respective abutment surfaces of the hot plates are below the upper edge of the expected sealing area, and thereafter, at least one of the pair of grippers and the pair of hot plates is moved vertically to a position where the abutment surfaces of the hot plates face the whole of the expected sealing area, and further, the hot plates are moved toward each other so that the abutment surfaces abut against the expected sealing area to seal the expected sealing area.

In addition, the present invention provides a bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging apparatus includes a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration. The bag filling and packaging apparatus further includes a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates, and a guide device provided between the deaeration station and the sealing station. The guide device has a pair of guide members provided facing each other at the opposite sides of the bag passing therebetween. The guide members extend over a predetermined length range in the direction of movement of the bag at a height position corresponding to the expected sealing area of the bag. The guide members extend gradually upward and gradually come closer to each other as the distance from the upstream side increases toward the downstream side in the direction of movement of the bag.

In addition, the present invention provides a bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging apparatus includes a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration. The bag filling and packaging apparatus further includes a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates, and a guide device provided between the deaeration station and the sealing station. The guide device has a pair of rollers provided facing each other across a predetermined space at the opposite sides of the bag passing therebetween and at a height position corresponding to the expected sealing area of the bag.

In addition, the present invention provides a bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging apparatus includes a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration. The bag filling and packaging apparatus further includes a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates. The steam-replacement deaeration device further has a pair of pressing members provided at the opposite sides, respectively, of the bag and at a height position corresponding to the expected sealing area. The pressing members are movable between respective pressing positions where the pressing members move toward each other to press the nozzle through the bag and respective retract positions where the pressing members are away from the nozzle.

In addition, the present invention provides a bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging apparatus includes a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration. The bag filling and packaging apparatus further includes a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates. The steam-replacement deaeration device further has a pair of partially sealing members provided at the opposite sides, respectively, of the bag and at a height position corresponding to the expected sealing area. The partially sealing members are configured to move toward each other to partially seal the expected sealing area of the bag at the laterally opposite sides of the nozzle.

In addition, the present invention provides a bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging apparatus includes a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration. The bag filling and packaging apparatus further includes a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates, and a bag mouth cooling device provided between the deaeration station and the sealing station. The bag mouth cooling device has a pair of cooling members disposed at the opposite sides, respectively, of the bag passing therebetween and each having a gas outlet port. The bag mouth cooling device further has a cooling gas supply source supplying a cooling gas to the cooling members through supply piping.

In addition, the present invention provides a bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes. The bag filling and packaging apparatus includes a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration. The bag filling and packaging apparatus further includes a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates. When sealing the expected sealing area of the bag, the hot plates of the sealing device respectively disposed at the opposite sides of the bag and placed at respective standby positions which are apart from the bag by a predetermined distance move toward each other to respective restricting positions where the hot plates are apart from bag by a restricted distance shorter than the standby distance and where the upper edges of respective abutment surfaces of the hot plates are below at least the upper edge of the expected sealing area of the bag, and after the hot plates have reached the restricting positions, at least one of the pair of hot plates and the pair of grippers moves vertically relative to the other of the pair of hot plates and the pair of grippers to a position where the abutment surfaces of the hot plates face the whole of the expected sealing area, and the hot plates further move toward each other to respective sealing positions where the hot plates press the bag therebetween.

As has been stated above, it is possible, according to the present invention, to minimize curl of the bag mouth edge generated under the influence of steam and to correct or remove curl generated at the bag mouth edge, and hence possible to achieve satisfactory sealing in the sealing step. In addition, an expected sealing area can be set without the need to avoid a curled portion. Therefore, the bag mouth can be sealed completely to the edge thereof. Accordingly, a sufficient seal width can be ensured, and the seal strength can be increased. In addition, it is possible to obtain a bag looking attractive as merchandise. Further, because the bag mouth edge is sealed, it is possible to prevent dust from entering the bag mouth while the bag is being displayed as merchandise

Other objects and advantages of the present invention will become apparent from the following detailed description of illustrated embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing the structure of a bag filling and packaging apparatus according to the present invention.

FIGS. 2 a and 2 b are plan and front views, respectively, showing a bag mouth correcting device according to a first embodiment of the present invention.

FIG. 3 a is a diagram showing the way in which a bag mouth is corrected in the first embodiment.

FIG. 3 b is a diagram showing a bag for which bag mouth correction has been completed in the first embodiment.

FIGS. 4 a, 4 b and 4 c are sectional views taken along the lines A-A, B-B, and C-C in FIGS. 2 a, 3 a and 3 b, respectively.

FIGS. 5 a and 5 b are plan and front views, respectively, showing a bag mouth correcting device according to a second embodiment of the present invention.

FIG. 6 a is a diagram showing the way in which a bag mouth is corrected in the second embodiment.

FIG. 6 b is a diagram showing a bag for which bag mouth correction has been completed in the second embodiment.

FIGS. 7 a and 7 a are diagrams showing a deaeration device according to a third embodiment of the present invention.

FIGS. 8 a and 8 b are diagrams showing a bag mouth correcting device according to a fourth embodiment of the present invention.

FIG. 9 is a plan view showing a cooling device according to a fifth embodiment of the present invention.

FIG. 10 is a sectional view showing the cooling device according to the fifth embodiment.

FIGS. 11 a, 11 b, 11 c and 11 d are diagrams showing the procedure for sealing performed by a sealing device according to a sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained below with reference to the accompanying drawings. It should, however, be noted that the following embodiments are for illustrative purposes only, and that the scope of the present invention is not limited to these embodiments.

FIG. 1 is a perspective view schematically showing the structure of a bag filling and packaging apparatus 1 according to the present invention. The bag filling and packaging apparatus 1 has a rotary table 2. In the following embodiments, the rotary table 2 rotates intermittently. However, the present invention is also applicable to a continuously rotating type rotary table. A plurality of pairs of laterally spaced grippers 3 are disposed at equal spaces in the circumferential direction of the rotary table 2. A publicly known conveyor magazine 4 is provided at a bag feeding station I. Bags B are taken out from the conveyor magazine 4 one by one by a pair of take-out suction cups 5 and delivered to a pair of grippers 3 in an upright position. At a printing station II, a printer 6 is provided to print the bag B with data, e.g. the date of manufacture. At a bag mouth opening station III, the mouth of the bag B is opened by using a pair of mouth opening suction cups 7. At a filling station IV, the bag B is filled with an article to be packaged through a hopper 8. At a deaeration station V is disposed a deaeration device 9 having a nozzle 10 connected to a steam source (not shown). At the deaeration station V, the nozzle 10 is inserted into the bag B, and steam is injected into the bag B to replace the air in the bag B with the steam, thereby effecting deaeration. This will be detailed later. At a sealing station VI is disposed a first sealing device 11 having a pair of hot plates 12 disposed facing each other across an expected sealing area set at the mouth of the bag B. Similarly, at a sealing station VII is disposed a second sealing device 13 having a pair of hot plates 14 disposed facing each other across the expected sealing area of the bag B. It should be noted that the second sealing device 13 is not necessarily needed. In the following embodiments, the first sealing device 11 will be described as a representative of the two sealing devices, being referred to simply as “sealing device 11”. At a cooling and discharging station VIII, the expected sealing area of the bag B is cooled with a pair of cooling plates 15 before being discharged onto a finished bag discharge chute 16.

Next, a first embodiment of the present invention will be explained with reference to FIGS. 2 a to 4 c. FIGS. 2 a to 4 c show the way in which the side wall sheets of the bag mouth that are tilted laterally outward due to expansion under the influence of steam in the deaeration step are corrected by a guide-type bag mouth correcting device 21 (hereinafter referred to simply as “correcting device 21”). FIGS. 2 a and 2 b show a bag B having moved to near the correcting device 21 after the air in the bag B has been replaced with steam for deaeration at the deaeration station V. FIG. 3 a shows the way in which the bag mouth is corrected by the correcting device 21. FIG. 3 b shows the bag B for which bag mouth correction has been completed. FIGS. 4 a, 4 b and 4 c show sections A-A, B-B, and C-C in FIGS. 2 a, 3 a and 3 b, respectively. It should be noted that, in this embodiment, an area extending over a predetermined width range from the bag mouth edge BM is defined as an expected sealing area S.

FIG. 2 a is a plan view, and FIG. 2 b is a front view. The correcting device 21 is provided between the deaeration station V and the sealing station VI, which are shown in FIG. 1. The correcting device 21 has a pair of bar-shaped guide members 22. The guide members 22, as will be understood from the figures, extend in the direction of movement of the bag B by a predetermined distance above the grippers 3 holding the bag B moving toward the correcting device 21. The guide members 22 are formed so that the guide members 22 extend gradually upward and gradually come closer to each other (i.e. the space therebetween gradually decreases) as the distance from the upstream side increases toward the downstream side as seen in the direction of movement of the bag B. That is, as shown in FIGS. 2 a and 2 b, the guide members 22 extend in the vertical direction over a range from a position slightly below the lower edge of the expected sealing area S when the bag B is in a normal state to a position slightly above the bag mouth edge BM. As to the space therebetween, the guide members 22 are formed such that, at the inlet side (left-hand side in the figures), the space is sufficiently wide to surely receive the bag B moving toward the correcting device 21, and at the outlet side (right-hand side in the figures), the space is slightly wider than the thickness of the bag B, thereby allowing the bag B to smoothly move through the space between the guide members 22.

As shown in FIGS. 3 a and 4 b, as the bag B advances further rightward, the bag mouth edge BM of the bag B is gradually raised from the tilted position and thus corrected to a condition in which the side wall sheets of the bag mouth are very close to each other. When the bag B has passed through the correcting device 21, the bag mouth has been corrected over the entire width, and, in this state, the bag B arrives at the sealing station VI, where the expected sealing area S is sealed with hot plates (not shown).

According to the above-described embodiment, even if the bag mouth is curled due to the influence of steam in the deaeration step, the curl is corrected in the bag mouth correcting step, and, in this state, the expected sealing area S is sealed in the sealing step. Therefore, satisfactory sealing can be achieved, and the bag mouth can be sealed completely to the edge BM.

Next, a second embodiment of the present invention will be explained with reference to FIGS. 5 a to 6 b. A bag mouth correcting device 25 in this embodiment differs from the correcting device 21 in the first embodiment only in that a pair of guide rollers 27 is used in place of the pair of bar-shaped guide members 22. The correcting device 25 is the same as the correcting device 21 with regard to other structural features, e.g. the feature that the correcting device 25 is provided between the deaeration station V and the sealing station VI. Therefore, only the points in which the correcting device 25 of the second embodiment differs from the correcting device 21 of the first embodiment will be explained below.

FIGS. 5 a and 5 b correspond to FIGS. 2 a and 2 b, respectively, which show the first embodiment. FIG. 5 a is a plan view, and FIG. 5 b is a front view. FIGS. 6 a and 6 b correspond to FIGS. 3 a and 3 b, respectively. FIG. 6 a shows the way in which the bag mouth is corrected. FIG. 6 b shows the bag B sent to the sealing step after the bag mouth has been corrected. As has been stated above, the correcting device 25 in the second embodiment has a pair of guide rollers 27 disposed at the opposite sides, respectively, of the bag B. The guide rollers 27 are rotatably attached to rotating shafts 28 secured to roller mounting shafts 26, respectively, which are secured to a base (not shown) of the bag filling and packaging apparatus 1. The guide rollers 27 are rotatable in a horizontal plane. The two guide rollers 27 are, as shown in the figures, disposed above the grippers 3 at a height position corresponding to the expected sealing area S, and spaced from each other with a gap slightly wider than the thickness of the bag B. It should be noted that the thickness (vertical dimension) of each guide roller 27 may be the distance from a position slightly below the lower edge of the expected sealing area S to a position slightly above the bag mouth edge BM. As will be clear from the above-described structure, according to the second embodiment, the curl of the bag mouth is corrected by the same procedure as in the first embodiment.

Next, a third embodiment of the present invention will be explained with reference to FIGS. 7 a and 7 b. In this embodiment, the deaeration device 9 is configured to prevent the bag mouth edge BM from being curled during steam-replacement deaeration, or to minimize curl of the bag mouth edge BM if curled. FIG. 7 a shows the way in which the lower end (nozzle hole-side end) of a nozzle 10 is inserted into the bag B moved to and stopped at the deaeration station V, and in which the grippers 3 are moved away from each other by a predetermined distance to bring the bag mouth into a tensed state. The nozzle 10 is secured to a support plate 31 and can be vertically moved, together with the support plate 31, by a drive source (not shown). The nozzle 10 is connected to a steam supply source 32 through a supply line 34. The supply line 34 is provided with a switching valve 33. The deaeration device 9 is provided with a pair of pressing members 35 that press the expected sealing area S of the bag B, with the nozzle 10 inserted therein, from both sides of the bag B. The pair of pressing members 35 are elongated bar-shaped members with a rectangular cross-sectional configuration (as shown in the figures), which are made of an elastic material, e.g. rubber. However, the present invention is not limited to the above-described constituent material and configuration. Any pressing structure may be used, provided that the side wall sheets of the expected sealing area S of the bag B can be brought into close contact with and pressed against the outer surfaces of the nozzle 10 from both sides along the configuration of the nozzle 10 (although in this embodiment the nozzle 10 has a flat cross-sectional configuration, the present invention is not limited thereto).

The pair of pressing members 35 are movable between respective retract positions, shown in FIG. 7 a, where the pressing members 35 are away from the bag B, and respective pressing positions, shown in FIG. 7 b, where the pressing members 35 press against the nozzle 10 through the side wall sheets of the bag B from both sides thereof, thereby bringing the side wall sheets of the expected sealing area S of the bag B into close contact with the side surfaces of the nozzle 10. That is, the pressing members 35 are moved from the respective retract positions shown in FIG. 7 a to the pressing positions shown in FIG. 7 b. Consequently, the side wall sheets of the expected sealing area S come in close contact with the outer surfaces of the nozzle 10 at the center in the width direction of the bag B (usually, the nozzle 10 is inserted into the bag B at the center in the width direction thereof). Accordingly, when injected into the bag B, steam cannot enter the close-contact area between the expected sealing area S and the nozzle 10, and thus the bag mouth is prevented from expanding at the center thereof. Steam flows out of the bag B at the laterally opposite sides of the nozzle 10; therefore, the bag mouth may expand at the laterally opposite sides of the nozzle 10. However, because expansion is suppressed at the center in the width direction of the bag B, the overall curl of the bag mouth is minimized. Therefore, there is no obstacle to sealing carried out in the subsequent step. The pressing members 35 are moved to the respective retract positions prior to removing the nozzle 10 from the bag B. It should be noted that the timing of injection of steam from the nozzle 10 may be determined appropriately. The injection of steam may be started simultaneously with or after the insertion of the nozzle 10 into the bag B, or after the nozzle 10 has been pressed through the bag B with the pressing members 35. The injection of steam may be stopped before or after the movement of the pressing members 35 to the respective retract positions, or at the same time as the nozzle 10 is removed from the bag B. It should be noted that the pressing members 35 are preferably each provided with an abutment surface extending over a range from a position below the lower edge of the expected sealing area S to a position above the bag mouth edge BM.

As will be clear from the foregoing explanation, the third embodiment is configured to prevent the bag mouth from being curled, or to minimize the degree of curl of the bag mouth if curled. Therefore, there is no possibility of a curled portion being folded and sealed in the folded condition in the subsequent sealing step, and thus satisfactory sealing can be achieved. It is also possible to surely seal the bag mouth to the edge BM.

Next, a fourth embodiment of the present invention will be explained with reference to FIGS. 8 a and 8 b. The feature of the fourth embodiment resides in that, after the nozzle 10 has been inserted into the bag B in the deaeration step, the bag B is partially and temporarily sealed at the laterally opposite sides of the nozzle 10. That is, as shown in FIGS. 8 a and 8 b, the deaeration device 9 in the fourth embodiment has two pairs of temporary sealing hot plates 41 and 42 for partially and temporarily sealing the expected sealing area S at the laterally opposite sides of the nozzle 10.

FIG. 8 a shows the way in which the nozzle 10 is inserted into the bag B moved to and stopped at the deaeration station V. In the illustrated state, the temporary sealing hot plates 41 and 42 are at respective retract positions. After the grippers 3 have moved away from each other to bring the bag mouth into a tensed state, the temporary sealing hot plates 41 and 42 move to respective sealing positions where the mating temporary sealing hot plates of each pair are close to each other, as shown in FIG. 8 b, to seal portions of the expected sealing area S at the laterally opposite sides of the nozzle 10. The abutment surfaces of the hot plates 41 and 42 that hold the bag B therebetween, as shown in the figures, vertically extend across the bag mouth edge BM. With this configuration, the side wall sheets of the central portion of the expected sealing area S come in close contact with the outer surfaces of the nozzle 10, or the gaps therebetween become very narrow, even if the side wall sheets are not in close contact with the nozzle outer surfaces. Accordingly, the entry of steam into the gaps is limited, so that the influence of steam is reduced. Further, because the expected sealing area S of the bag B is temporarily sealed at the laterally opposite sides of the nozzle 10, the width of the opening in the central portion is narrow. Therefore, even if the central portion of the expected sealing area S is curled, the degree of curl is very small. In addition, the width between each temporarily sealed portion of the expected sealing area S and the corresponding side edge of the bag B is also narrow; therefore, the degree of curl at this portion is also small. Accordingly, even if the bag mouth is sealed in this state, there is no possibility of the curled portion being folded and sealed in the folded condition, and thus satisfactory sealing can be achieved. It is also possible to seal the bag mouth completely to the edge BM. It should be noted that, in the fourth embodiment, the timing of starting the injection of steam is preferably after temporary sealing has been applied to the expected sealing area S of the bag B.

Next, a fifth embodiment of the present invention will be explained with reference to FIGS. 9 and 10. In the fifth embodiment, after steam-replacement deaeration has been carried out, the bag mouth is cooled to return the expanded and curled bag mouth to the original state. That is, the fifth embodiment has a cooling station provided between the deaeration station V and the sealing station VI, and a cooling device 45 is disposed in the cooling station. FIG. 9 is a plan view showing the cooling device 45. FIG. 10 is a side view showing the way in which the bag B is moving between cooling nozzles 46 of the cooling device 45 after having been subjected to steam-replacement deaeration by the deaeration device 9 at the deaeration station V.

The cooling device 45 has a pair of elongated cooling nozzles 46 disposed at the opposite sides, respectively, of the moving bag B somewhat above the bag B. The nozzles 46 extend in the direction of movement of the bag B. Each nozzle 46 has a plurality of gas outlet ports 47 provided at predetermined spaces in the longitudinal direction of the nozzle 46. The nozzles 46 are connected to a cooling gas supply source 48 through piping 49. The gas outlet ports 47, as will be understood from the figures, face obliquely downward to blow a cooling gas mainly toward the expected sealing area S of the bag B, including the curled bag mouth edge BM. By blowing the cooling gas in this way, the expected sealing area S, which is expanded and slantingly curled, is cooled and returned to the original uncurled state. In this state, the bag B is moved to the sealing station VI, where the expected sealing area S is sealed. Accordingly, satisfactory sealing can be achieved. As the cooling gas, air or the like is usable.

Next, a sixth embodiment of the present invention will be explained with reference to FIGS. 11 a to 11 d. The sixth embodiment is configured to correct the curled bag mouth by employing hot plates used in the sealing step. That is, in the sixth embodiment, the pair of hot plates 12 of the sealing device 11 respectively disposed at the opposite sides of the bag are first placed at respective standby positions (FIG. 11 a) which are apart from the bag by a predetermined distance and where the upper edges of respective abutment surfaces 12 a of the hot plates 12 are below the upper edge of the curled expected sealing area S of the bag B. It should be noted that, in the sixth embodiment, the upper edge of the expected sealing area S is the bag mouth edge BM because the expected sealing area S is provided to extend over a predetermined width range from the bag mouth edge BM. In the illustrated example, when the hot plates 12 are in the standby positions, the upper edges of the abutment surfaces 12 a of the hot plates 12 are at a position substantially corresponding to the lowermost part of the curled portion of the bag mouth (in many cases, the lowermost part is at substantially the center of the bag width). Next, the hot plates 12 move toward each other to respective restricting positions (FIG. 11 b) where the hot plates 12 are apart from the bag by a restricted distance slightly wider than the thickness of the bag B. The hot plates do not change the respective positions in the up-and-down direction. Next, the hot plates 12 move upward, while keeping the distance therebetween unchanged (FIG. 11 c), toward respective seal standby positions where the abutment surface 12 a of each hot plate 12 faces the expected sealing area S of the bag B (FIG. 11 d). Next, the hot plates 12 move toward each other to respective sealing positions where the hot plates 12 press the expected sealing area S of the bag B therebetween to seal the expected sealing area S. When moving from the restricting positions to the seal standby positions, the hot plates 12 correct the curled and laterally tilted side wall sheets of the bag mouth edge BM or the expected sealing area S so that the side wall sheets face close to each other, before sealing the expected sealing area S. Accordingly, satisfactory sealing can be achieved. It should be noted that the restricting positions of the hot plates 12 are not limited to the illustrated positions, but may be any positions that enable the hot plates 12 to correct the curled bag mouth when moving to the seal standby positions therefrom. Although in the above-described example the hot plates 12 are moved upward to the seal standby positions, the grippers 3 may by moved downward to thereby move the bag B downward instead of moving the hot plates 12 upward. 

What is claimed is:
 1. A bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes, the bag filling and packaging apparatus comprising: a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration; a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates; and a guide device provided between the deaeration station and the sealing station, the guide device having a pair of guide members provided facing each other across a predetermined space at opposite sides of the bag passing therebetween and at a height position corresponding to the expected sealing area of the bag.
 2. A bag filling and packaging apparatus according to claim 1, said guide members extend over a predetermined length range in a direction of movement of the bag at a height position corresponding to the expected sealing area of the bag, and the guide members extend gradually upward and gradually coming closer to each other as a distance from an upstream side increases toward a downstream side in the direction of movement of the bag.
 3. A bag filling and packaging apparatus according to claim 1, said guide members are a pair of guide rollers.
 4. A bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes, the bag filling and packaging apparatus comprising: a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration; and a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates; the steam-replacement deaeration device further having a pair of pressing members provided at opposite sides, respectively, of the bag and at a height position corresponding to the expected sealing area, the pressing members being movable between respective pressing positions where the pressing members move toward each other to press the nozzle therebetween through the bag and respective retract positions where the pressing members are away from the nozzle.
 5. A bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes, the bag filling and packaging apparatus comprising: a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration; and a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates; the steam-replacement deaeration device further having a pair of partially sealing members provided at opposite sides, respectively, of the bag and at a height position corresponding to the expected sealing area, the partially sealing members being configured to move toward each other to partially seal the expected sealing area of the bag at laterally opposite sides of the nozzle.
 6. A bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes, the bag filling and packaging apparatus comprising: a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration; a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates; and a bag mouth cooling device provided between the deaeration station and the sealing station; the bag mouth cooling device having a pair of cooling members disposed at opposite sides, respectively, of the bag passing therebetween and each having a gas outlet port, and a cooling gas supply source supplying a cooling gas to the cooling members through supply piping.
 7. A bag filling and packaging apparatus in which a bag is held, with its bag mouth facing upward, by being gripped at laterally opposite side edges thereof with a pair of laterally spaced grippers, and the bag held in this way is moved along a predetermined planar path to sequentially undergo predetermined packaging processes, the bag filling and packaging apparatus comprising: a steam-replacement deaeration device provided at a deaeration station and having a nozzle to be inserted into a bag filled with an article to be packaged to inject steam into the bag to replace air in the bag with the steam, thereby effecting deaeration; and a sealing device provided at a sealing station to seal an expected sealing area set at a bag mouth of the bag with a pair of hot plates; wherein, when sealing the expected sealing area of the bag, the hot plates of the sealing device respectively disposed at the opposite sides of the bag and placed at respective standby positions which are each apart from the bag by a predetermined standby distance are moved toward each other to respective restricting positions where the hot plates are each apart from the bag by a restricted distance shorter than the standby distance and where upper edges of respective abutment surfaces of the hot plates are below at least an upper edge of the expected sealing area of the bag, and after the hot plates have reached the restricting positions, at least one of the pair of hot plates and the pair of grippers is moved vertically relative to the other of the pair of hot plates and the pair of grippers to a position where the abutment surfaces of the hot plates face a whole of the expected sealing area, and the hot plates are further moved toward each other to respective sealing positions where the hot plates press the bag therebetween. 